Confirming the industry's worst-kept secret, Valve CEO Gabe Newell has confirmed Valve is working on its 'Steam Box', a Steam-powered HTPC geared towards console-like gaming. It'll most likely run Linux. "Well certainly our hardware will be a very controlled environment," he told Kotaku. "If you want more flexibility, you can always buy a more general purpose PC. For people who want a more turnkey solution, that's what some people are really gonna want for their living room." Steam has 50 million subscribers, so there's a market here. As a comparison: Xbox Live has 40 million subscribers.

Alas, apples and oranges. Applications can be almost anything, including your typical fart - apps, whereas games are a very definite subcategory of applications.

Also, yes, the ones that have been ported over have likely been the easy ones: the small-time, Indie developers generally have source-code to their own engines and the engines are specific to the game in question, so porting them over is much easier. Contrast that to popular engines that are not specific to any game type or content and which ones are only licensed by the developers of the games; it's the job of the owner of the engine itself to do the porting first, and only then can the licensee port the game.

These things need context. What kind of momentum is there behind the ports?

We do not know. Most of the developers do not reveal such information, so we're mostly flying in dark here in regards to this question. I've heard rumours that the new Unreal engine would support Linux and that would be big news, but alas, they are rumours only and I cannot find anything official. Their own website doesn't mention Linux at all. That said, they sport in-engine support for Steamworks and OpenGL, they support OSX and Android -- both of which are Unix-like platforms -- and so on, so doing a Linux-port wouldn't be too far-fetched.